This Is Why You Don’t Use PVC

PVC is lightweight, inexpensive, and easy to purchase at any local building supply store, making it all the more attractive when it comes to selecting piping materials for a compressed air system.

Using PVC, however, has its risks and in certain areas it may not be code compliant. It’s subject to bursting (yes bursting), and the adhesives used in installation are not compatible with all types of compressor oils. It can be a conduit for static charge which might cause electrical shock or even fire in environments with combustible vapors or dust. Despite the safety issues, many small shops and even some larger plants continue to use it.

A couple years back we were installing a compressor at a medical device manufacturer in Colorado, and we noted the plant’s wide use of PVC piping. I asked the shop manager (who was three weeks from retiring) whether they’d had any issues with PVC cracking or bursting under pressure. He said yes, many times. “Pieces fly across the room.” He would just replace them. “No one’s been hurt so far…”

In a room with 4 huge, expensive injection molding machines and many employees, he saw no need to change. Different strokes, I guess.

Here are two more examples:

1. The remains from a 2” PVC pipe burst at a manufacturing plant in Texas. Thankfully no injuries, but some unscheduled changing of underwear.

2. In a small custom paint shop in Texas, a large section of PVC pipe burst during normal operation. The high heat and vibration from the piston compressor probably played a part.

If you have PVC pipe in your shop or factory, make sure it’s pressure rated and regularly check it for signs of cracking.

For those of you considering using PVC pipe, I urge you not to—it’s really not worth the risk.

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5 thoughts on “This Is Why You Don’t Use PVC”

Even checking for cracks regularly does not protect a shop owner or his employees from potential explosions or pipe separations. When PVC ruptures, it does not just split open like metal piping…it sends shrapnel flying.
I had a customer who received a visit from OSHA and was told he had to replace the PVC in his woodworking shop. The letter posted on the wall from OSHA said to not exceed 12 psi with the PVC. This customer had previously experienced a failure during the night when no one was in the shop (fortunately) but still refused to replace the PVC until forced to by OSHA.
On another occasion, I was working a trade show when a visitor stopped by to take a look at our Kaeser SmartPipe. He showed me a 2″ long scar on his knee that was the result of PVC piping exploding in his shop. He was lucky…it could have been much worse. Ironically, he still was using PVC piping in his shop!

Copper piping is a great choice. It won’t rust, will give years of good air quality, and its smooth interior means you won’t have problems with pressure drop. The materials can be expensive to purchase and it does require quality brazing—if it isn’t properly installed you will have problems with leaks. Quality brazing takes time, and depending on the size of the installation, this can make the installation quite expensive.
An alternative to copper—which doesn’t require brazing and still is corrosion resistant, easy to install, and has very low pressure drop—is aluminum. The material costs a bit more, but you usually make up for it in the installation savings.
Regardless of the piping material, it needs to be properly sized for the flow in order to prevent pressure drop.

Not one mention of what schedule pvc pipe has been most often used. I assisted in the use of PVC piping in an air system. Schedule 40 on 3/4″ and below schedule 80 on any other size. Every joint had a minimum of 3 evenly spaced S/S sheet metal screws. Joint glue was cpvc/pvc formula. System pressure, 175 psi. Flow fuses were used in the main header pipes as a rupture control measure. We grounded the system at several points based on info from a woodworking pub which used pvc as a sawdust/chip removal system.

I’m sure it is a quality installation—the concern here is using the pipe for its proper application. OSHA and numerous state agencies and the Plastics Pipe Institute have indicated PVC shouldn’t be used for compressed air unless it is encased underground because of the safety risks. Because rules vary by state, I recommend checking out local regulations before using the material.